Safety belt system for wheelchair lifts

ABSTRACT

A vehicle access system for moving a passenger between the vehicle and ground. Some embodiments have an electrical system, a motive source coupled to the electrical system, an arm coupled to the motive source, a platform coupled to the arm, and a safety restraint system coupled to the electrical system and the platform. The vehicle access system has at least a vehicle access position and a ground access position, wherein the passenger can safely access the platform at either access position. The platform is unable to move from either access position until the safety restraint system is in place. Once operation of the access system has begun, it can continue to operate and move the passenger to one of the access positions even if the safety restraint system is subsequently removed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional Application Ser.Nos. 60/361,989 filed 5 Mar. 2002 and 60/355,175 filed 7 Feb. 2002.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present application relates generally to the field of vehicularaccess systems for handicapped persons, and more particularly to thefield of safety devices related to those systems.

2. Description of the Related Art

People who have difficulty walking and people who use wheelchairs oftenhave difficulty moving between different levels, such as getting intoand out of vehicles. Consequently, there is a great need for devicesthat are capable of transporting people into and out of vehicles.Therefore, many different vehicular wheelchair access systems, such aslifts and ramps, have been developed to fulfill this need. These systemscan be mounted on vehicles and manipulated between deployed and stowedpositions with respect to the vehicle. When these systems are in thedeployed position, wheelchair users typically must move their wheelchairalong the lift and ramp platforms in order to transfer from the groundto the vehicle and from the vehicle to the ground. During the use ofconvention vehicle access systems, the passenger or operator canencounter potential dangers, such as falling off of the lift or ramp.Therefore, it is desirable to provide a safety system to assist liftoperators and users in operating the access system in a safe manner. Theinvention of the present application is directed to satisfying theseneeds, among others.

Many vehicle access systems such as passenger lifts and ramps are knownin the art. However, there is a constant desire in the art to make thesesystems more reliable, cost effective and safe. Many safety features arecurrently used on several access systems, such as safety belts, barrierplates, and sensors. These restraining devices help prevent wheelchairsfrom rolling off the access system while in operation or can preventoperation of the access system altogether. However, they can havecertain problems that can make them unsafe.

Some vehicle access systems utilize belt buckle with an electronicsafety interlock to prevent all movement of the access system until thesafety belt is fastened to the buckle. In such devices, the safetyinterlock is a normally open electric switch located in the buckle.Thus, when the safety belt is unbuckled, the switch is open and the liftis incapable of operation. Once the safety belt is buckled, the switchis closed and the system is capable of operating. However, if the beltis unbuckled in the middle of operation, the system will stop operating.This can create a dangerous situation wherein the passenger is stuck inan elevated position in which the passenger cannot safely access eitherthe vehicle or the ground. Furthermore, the passenger is stuck in thisposition, unrestrained by the safety belt. Thus, despite other safetyfeatures, the passenger may be able to roll off the access system whilethe system is in a position in which its is not safe to dismount. Insuch devices, operation of the system will not and cannot continue untilthe safety belt is buckled once again.

In light of the problems and limitations described above, a need existsfor a vehicle access system that is reliable, cost effective, and safeso that either safety restraint systems cannot be removed while inoperation or that operation does not automatically cease between accesspositions even if the safety belt is removed during operation of thesystem. Each embodiment of the present invention achieves one or more ofthese results.

SUMMARY OF THE INVENTION

The vehicle access system according to some embodiments of the presentinvention has an electrical system, a motive source coupled to theelectrical system, an arm coupled to the motive source, a platformcoupled to the arm, and a safety restraint system coupled to theelectrical system and the platform. The vehicle access system can bemounted to the vehicle and operable to move a passenger between theground and the vehicle. If the vehicle access system is mounted to thevehicle, it can have three or more main positions and numerousintermediate positions. The main positions can include a stowedposition, vehicle access position (loading/unloading position into andout of the vehicle), and a ground access position (loading/unloadingposition onto and off of the ground). Thus, the passenger can safelyaccess the platform at either access position. Once the passenger issituated and restrained on the platform, the platform can be movedbetween levels and the passenger can safely dismount the platform at theother access position. The platform, however, is unable to move fromeither access position until the safety restraint system is in place.

Some embodiments of the present invention utilize a belt and buckle thathas a current path through it as part of a safety restraint system. Thecurrent path is open when the belt and buckle are unbuckled and closedwhen they are buckled. The current path through the safety belt, in someembodiments, is coupled to a silicon controlled rectifier diode that iscoupled to the electrical system of motive source. The diode has aturned-on and a turned-off state. The motive source can be powered whenthe diode is turned-on and cannot be powered when the diode has beenturned-off. The diode is turned-on and off by a gate coupled to thecurrent path in the buckle. When the current path through the buckle isclosed, current flows to the gate of the diode to turn-on the diode andallow current to flow to the motive source. Once the diode is turned-onand so long as current continues to be drawn to the motive source, thediode can remain turned-on regardless of the state of the current paththrough the buckle. Thus, once operation of the access system has begun,it can continue to operate and move the passenger to one of the safeaccess positions even if the buckle is subsequently released.

Other embodiments of the present invention can utilize one or moreadditional safety features alone or in combination with the abovementioned features. For example, some embodiments utilize roll-stopscoupled to the platform, while other embodiments utilize a lock on thesafety belt to prevent unbuckling during operation to prevent thepassenger from rolling off the platform. Yet other embodiments utilizevarious audible and/or visual signals to alert the operator that thesafety belt is unbuckled. Finally, other embodiments can utilizepressure switches coupled to the platform to prevent movement of theplatform to the stowed position while the passenger is on the platform.

A better understanding of the principles of the invention will becomeapparent from the following detailed description of the illustratedembodiments of the invention when taken in conjunction with theaccompanying drawings, wherein like elements have like numeralsthroughout the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described with reference to theaccompanying drawings, which show preferred embodiments of the presentinvention. However, it should be noted that the invention as disclosedin the accompanying drawings is illustrated by way of example only. Thevarious elements and combinations of elements described below andillustrated in the drawings can be arranged and organized differently toresult in embodiments which are still within the spirit and scope of thepresent invention.

In the drawings, wherein like reference numeral indicate like parts:

FIG. 1 is a perspective view of a vehicular wheelchair access and safetybelt system with the platform unfolded and extending from the vehicle ina horizontal entry level position and the safety belt engaged;

FIG. 2 is a perspective view of the system of FIG. 1 with the platformat the ground level position and the safety belt engaged;

FIG. 3 is a perspective view of the system of FIG. 1 with the platformfolded to a vertically stowed position and the safety belt engaged;

FIG. 4 is an electrical schematic including for the wheelchair accesssystem including the safety belt system of the present invention; and

FIG. 5 is one embodiment of a wiring diagram for the electrical systemof FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any such alterations and furthermodifications in the illustrated embodiments, and such furtherapplications of the principles of the invention as illustrated hereinare contemplated as would normally occur to one skilled in the art towhich the invention relates.

Referring now to FIG. 1 there is illustrated a vehicular access system10. Although access system 10 is illustrated as a wheelchair lift typesystem, it is also contemplated that principles discussed herein haveapplication in wheelchair ramp type systems. Access system 10 is mountedin the door of a vehicle (not shown) to provide wheelchair passengeraccess to and from the vehicle. Access system 10 has a platform 22movable in the inboard and outboard directions relative to the vehicle,as indicated by arrow I (inboard direction) and arrow 0 (outboarddirection.) Examples of wheelchair access systems are provided in U.S.Pat. No. 6,238,169; U.S. Pat. No. 5,806,632; U.S. Pat. No. 5,261,779;U.S. Pat. No. 6,065,924; and U.S. Provisional Application Ser. No.60/355,175 filed Feb. 7, 2002, each of which is incorporated herein byreference in its entirety. Another example of a wheelchair access systemis The Braun Corporation's EV BRAUN ENTERVAN® wheelchair access ramp.

In the illustrated embodiment, access system 10 includes a motive source12 operatively coupled to paired parallelogram type lifting mechanisms14. Parallelogram lifting mechanisms 14 include vertical arms 20 towhich an inboard end of platform 22 is pivotally coupled. When not inuse, it is desirable to stow platform 22 in the vehicle in a verticalorientation adjacent the door of the vehicle to minimize its intrusioninto the vehicle. Platform 22 can also be provided with foldablesections for stowage in a reduced height configuration, such asdescribed in the aforementioned Provisional Application No. 60/355,175filed Feb. 7, 2002.

Access system 10 also includes articulated lever assemblies 16 pivotallyconnected to the inboard end of platform 22 at one end and to acorresponding one of the vertical arms 20 at their other end.Articulated lever assemblies 16 can include a longer arm pivotallyconnected to a shorter arm at a common center along with a saddle blockfor contacting the bottom arm of parallelogram lifting mechanisms 14,such as shown and described in the aforementioned U.S. Pat. No.6,238,169 and Provisional Application No. 60/355,175 filed Feb. 7, 2002.A safety shield 18 extends from a corresponding one of the vertical arms20 along each side of articulated lever assemblies 16 to protect againstthe potential placement of a part of a person or object therebetweenbefore and/or during lift operation.

Motive source 12 is operable to swing lifting mechanisms 14 generallyalong path R to move platform 22 from the vertically stowed position ofFIG. 3, to the transfer level position or horizontal entry levelposition of FIG. 1, to the ground level position of FIG. 2, and back.Motive source 12 can be electrically coupled to the vehicle power sourceand include hydraulic pumps and/or electrical motors and othercomponents to accomplish the desired movement for lifting mechanisms 14.

Mounting members 93 are secured to a floor plate 56 of the vehicle.Lifting mechanisms 14 are pivotally mounted to a corresponding one ofmounting members 93. Each lifting mechanism 14 includes an upper arm 88and a lower arm 90. Upper arms 88 are each pivotally coupled at theirinboard end to a corresponding one of the mounting members 93. Lowerarms 90 are also each pivotally coupled at their inboard end to acorresponding one of the mounting members 93 below upper arm 88. Eachlifting mechanism 14 also includes a cylinder 92 pivotally coupled atits outboard end to lower arm 90 and also to vertical arm 20. Theinboard end of each cylinder 92 is pivotally coupled to the inboard endof the respective upper arm 88 at mounting member 93. A deploy assistmechanism 86 can be provided around each cylinder 92. Further detailsregarding cylinder 92 and deploy assist mechanism 86 are provided in theaforementioned Provisional Application 60/355,175 filed Feb. 7, 2002.

When platform 22 is in its vertically stowed position, there may be atendency for platform 22 to drift in the outboard direction due to, forexample, a slow loss of hydraulic pressure in cylinder 92. When theplatform drifts, it could push against the vehicle door, making openingof the door difficult and also damaging the interior of the vehicle.Thus, there is provided anti-drift mechanism 100. One embodiment ofanti-drift mechanism 100 is shown in the aforementioned ProvisionalApplication No. 60/355,175 filed Feb. 7, 2002. Other embodimentanti-drift mechanisms are provided in U.S. patent application Ser. No.09/702,397 filed on Oct. 31, 2000, which is incorporated herein byreference.

Platform 22 is pivotally coupled at its inboard end to each of thevertical arms 20. Platform 22 has side barriers 28 extending along eachside thereof. Platform 22 can be provided with meshed grid-like or solidplate-like transfer surface between the side barriers and between theinboard/outboard ends of platform 22.

Access system 10 also includes a spring-loaded rollstop 46 pivotallyconnected to the outboard end of platform 22 that is normallyspring-biased to a raised safety barrier position as shown in FIG. 1.Rollstop 46 includes feet 46 a, 46 b (FIG. 1) that contact the ground tomove rollstop 46 to lower rollstop 46 to transfer level positionextending from the outboard end of platform 22 as shown in FIG. 3.

Access system 10 includes a bridge plate 50 pivotally coupled to theinboard end of platform 22. A pair of actuator assemblies can beprovided to couple bridge plate 50 to each of the articulated leverassemblies 16. The actuator assemblies and articulated lever assemblies16 operate in concert such that contact between articulated leverassemblies 16 and bottom arms 90 of lifting mechanisms 14 variouslyraise and lower bridge plate 50 between a raised safety barrier position(FIG. 2) and a generally horizontal transfer level position (FIG. 1.)Further details regarding bridge plate 50 are provided in theaforementioned Provisional Application 60/355,175 filed Feb. 7, 2002 andalso in U.S. Pat. No. 6,238,169. Other mechanisms for raising andlowering bridge plate 50 are also contemplated.

Access system 10 further includes handrails 42 extending horizontallyfrom vertical arms 20 when platform 22 is deployed in a horizontalposition as shown in FIGS. 1 and 2. When folded, as shown in FIG. 3,handrails 42 each extend along a corresponding one of the vertical arms20. A bumper 78 can be coupled to the upper side of each handrail 42 toeliminate or reduce noise and abrasion when the handrail is positionedagainst vertical arm 20. Each handrail 42 further includes an outboardend bent to conform to the upper end of vertical arm 20 when foldedthereagainst. A grip handle can be placed over the outboard ends of eachhandrail 42 to facilitate gripping thereof.

A safety belt system 200 is provided with access system 10. System 200includes a safety belt 202 extending between handrails 42. Safety belt202 is mounted at one end to one of the handrails 42 and removablyengaged to a buckle 204, which is mounted on the other handrail 42. Itis contemplated that safety belt 202 can include a strap and end memberlike that of an automobile seat belt for engagement with buckle 204.Other configurations are also contemplated, so long as safety belt 202is removably engageable with buckle 204. Safety belt 202 can benon-retractable, although a retractable belt is also contemplated.Buckle 204 can have any configuration suitable for engagement with theend member of safety belt 202. Buckle 204 includes a current paththerein that is coupled with the electrical system 210 of motive source12 by, for example, electrical wiring 206. It is contemplated thecurrent path in buckle 204 is normally open, and is closeable uponengagement of the end member of safety belt 202 with buckle 204. Closingthe current path in buckle 204 enables electrical system 210 to providepower to move platform 22 with motive source 12.

Platform 22 has three main positions including the vertically stowedposition (FIG. 3), the horizontal transfer level position (FIG. 1), andthe ground level position (FIG. 2.) Access system 10 includes sensorsproviding signals to electrical system 210 indicating when the platformis at one of the three main positions. The platform position signalsfrom platform sensors for the stowed position and the floor levelposition may be used to stop platform movement when the desired positionis reached.

When the current path in buckle 204 is closed by engaging the end memberof belt 202 to buckle 204, electrical system 210 can provide power tomotive source 12 to move platform 22 between the three main positionswith lifting mechanisms 14 based on operator signal input indicating thedesired platform movement. When safety belt 202 is not coupled withbuckle 204, the current path of electrical system 210 in buckle 204 isopen and platform movement cannot be initiated by operator inputsignals.

The safety belt system of the present invention enhances operatorcontrol of the lift during platform movement. If the current path inbuckle 204 is closed with the end member of safety belt 202, andplatform movement has been initiated by operator signal inputs, and thecurrent path in buckle 204 is thereafter opened during platform movementby disengaging the end member of belt 202, the current path inelectrical system 210 is maintained for platform movement to one of thethree main positions. However, platform movement can be stopped at anyposition intermediate the three main positions by the operator. Thus,the operator maintains control over lift operation even if safety belt202 is unbuckled.

When safety belt 202 is unbuckled, and when platform is at one of thethree main positions or has been stopped by the operator at anintermediate position, the current path of electrical system 210 is opento prevent platform movement. Platform movement can continue when theend member of belt 202 is engaged to buckle 204 to close the currentpath in buckle 204.

In FIG. 4, there is shown an electrical schematic of one embodiment ofelectrical system 210 for providing power to move platform 22. In FIG. 5there is shown one embodiment of a wiring diagram for electrical system210 of FIG. 4. Electrical system 210 is electrically coupled to safetybelt system 200. In the illustrated embodiment, electrical system 210includes an operator input device 212 electrically coupled to amicroswitch station 214. It is contemplated that input device 212 couldalso employ infrared or radio signals to communicate input signals fromthe operator. It is further contemplated that a programmable controllercould be provided in lieu of or in addition to microswitches 214.Electrical system 210 further includes a power source 218. It iscontemplated that power source 218 can be the vehicle's main battery orbackup battery, or a stand-alone battery dedicated to electrical system210. Input device 212, microswitches 214 and power source 218 areelectrically coupled to a pump housing 215.

Pump housing 215 includes a drive means 220, an up/fold controller 222,a down controller 224 and an unfold controller 226. In the illustratedembodiment, controller 222 is a controller which controls operation ofdrive means 220, and controllers 224 and 226 are solenoids that controloperation of valves of a hydraulic system coupled between drive means220 and cylinder 92. Drive means 220 includes a hydraulic pump and motorto supply hydraulic pressure to cylinders 92 to raise platform 22 fromthe ‘ground level position to the entry level position, and also tovertically fold platform 22 from the entry level position. An interlock228 is provided to allow coupling of additional sensors and the like toelectrical system 210. For example, a sensor can be mounted on thevehicle door and coupled to electrical system 210 via interlock 228.Control of the operation of platform 22 can be based on satisfaction ofan external condition determined by the sensor, such as whether thevehicle door is completely open.

Safety belt system 200 is electrically coupled between power source 218and pump housing 215 to control the operation of drive means 220. In theillustrated embodiment, safety belt system 200 includes a safety beltswitch 230 in buckle 204, a current flow control device 232 in the formof an SCR diode, and a resistor 234. Current flow control device 232includes gate G that prevents current flow therethrough when the currentpath in buckle 204 is open. When the current path in buckle 204 is open,current flow control device 232 disables electrical system 210 byblocking the current path to operate drive means 220 and controllers222, 224, and 226 with operator input signals from input device 212.

When the current path in buckle 204 is closed, current from power source218 flows through resistor 234 and switch 230 to energize and open gateG of current flow control device 232. With gate G open, current can flowthrough current flow restrictor 232, and power is provided from powersource 218 to operate controllers 222, 224 and 226 based on operatorinput signals from signal input device 212. Such signals initiatefolding or unfolding of platform 22 between the vertically stowed andhorizontal entry level positions, and the moving platform 22 up or downbetween the horizontal entry level and ground level positions. If thecurrent path in buckle 204 is opened by unbuckling belt 202 from buckle204, gate G remains opened until one of the platform positions is sensedat either stowed or floor level position or until platform operation isstopped by the operator. However, once one of the main positions ofplatform 22 is sensed or platform movement is stopped by the operatorthrough signal input device 212, power cannot be supplied to drive means220 and controllers 222, 224, 226 until the circuit in buckle 204 isclosed by engaging belt 202 to buckle 204.

In the illustrated embodiment, signal input device 212 includes anunfold input and a fold input selectable by the operator to providesignals indicative of the desired platform movement from the verticallystowed position to the horizontal transfer level position and back,respectively. Signal input device 212 also includes a down input and anup input selectable by the operator to provide signals indicative of thedesired platform movement from the horizontal entry level position andthe ground level position and back, respectively.

It is contemplated that microswitch station 214 includes unfold/downmicroswitches and up/fold microswitches coupled to controllers 222, 224,226 to control platform 22 movement in accordance with the commandsreceived from signal input device 212 as selected by the operator. Inthe illustrated embodiment, the up/fold microswitch signals the up/foldcontroller 222 to start or stop drive means 220. The unfold/downmicroswitch signals down controller 224 to open and close a first valvein the hydraulic system, and also signals unfold controller 226 to openand close a second valve in the hydraulic system.

In operation, when the up input is selected by the operator and safetybelt 202 is engaged to buckle 204, controller 222 starts drive means 220wherein the hydraulic pump provides pressurized hydraulic fluid tocylinder 92 to move platform 22 from the ground level position to thehorizontal entry level position. Belt 202 can be disengaged from buckle204 during this movement without affecting platform movement to theentry level position. When the platform reaches the entry level positionsensors provide a signal to direct controller 222 to stop drive means220.

When the fold input is selected by the operator and safety belt 202 isengaged to buckle 204, controller 222 starts drive means 220 to providepressurized hydraulic fluid to cylinder 92 to move platform 22 from thehorizontal entry level position to the vertically stowed position. Belt202 can be disengaged from buckle 204 during this movement withoutaffecting platform movement to the vertically stowed position. When theplatform reaches the vertically stowed position sensors provide a signalto direct controller 222 to stop operation of drive means 220.

When platform 22 is in the vertically folded position and safety belt202 is engaged to buckle 204, operator selection of the unfold inputsignals down controller 224 to open the first valve in the hydraulicsystem and also signals unfold controller 226 to open the second valvein the hydraulic system. Belt 202 can thereafter be disengaged frombuckle 204 without affecting platform movement to the entry levelposition. Unfolding of platform 22 is controlled by directing thehydraulic fluid through the second valve, which includes or is in fluidcommunication with a restricted orifice. The restricted orifice causesthe pressure to be relieved more slowly than would result if only thefirst valve were opened, thus' slowing movement of platform 22 from thevertically stowed position to the horizontal entry level position. Whenthe platform reaches the entry level position sensors provide a signalto direct controllers 224, 226 to shut the first valve and the secondvalve.

When platform 22 is at the horizontal entry level position and safetybelt 202 is engaged to buckle 204, a down input from the operatorsignals down controller 224 to open the first valve to relieve hydraulicpressure from cylinder 92 to allow platform movement from the horizontalentry level position to the ground level position. Belt 202 can bedisengaged from buckle 204 during this movement without affectingplatform movement to the ground level position. There is no ground levelsensor. See note on page 8.

In one alternate embodiment, electrical system 210 does not include anunfold controller 226 coupled to a restricted orifice, but rather only adown controller 224 to open the first valve to relieve pressure fromcylinder 92. Hydraulic pressure is relieved through this first valve forplatform movement both from the vertically stowed position to the entrylevel position, and from the entry level position to the ground levelposition. In such an alternate embodiment, the restricted orifice is notneeded since controller 224 and the first valve coupled thereto allowplatform 22 to unfold from the vertically stowed position at a ratewithin a desired range. Factors that influence whether the unfold rateof movement of platform 22 can be maintained in the desired range usingonly controller 224 and the first valve include the size of platform,the rates at which the desired range is established, and whether thefirst valve can be modulated for varying flow rates therethrough.Another factor is whether platform 22 is folded to a reduced heightconfiguration when vertically stowed such as described in theaforementioned Provisional Application 60/355,175 filed Feb. 7, 2002. Ifplatform 22 is provided as described therein, then only a single downcontroller 224 is needed since the reduced height, folded platform willunfold from the vertical position at a slower rate than if the platformwere not folded to a reduced height configuration.

Referring back to the illustrated embodiment, it is contemplated thatthe microswitches or other controller means can be configured so thatwith platform 22 in the entry level position signals from the unfoldinput and the up inputs of signal input device 212 are ignored ordisabled. In the ground level position, signals from the fold input,unfold input and down input of signal input device 212 are ignored ordisabled. In the vertically stowed position, signals from the foldinput, down input and up input of signal input device 212 are ignored ordisabled.

From the horizontal entry level position, the operator can then eitherfold the platform to the vertically stowed position or again move theplatform to the ground level position as discussed above. When platform22 is at the horizontal entry level position, a wheelchair passenger canbe positioned on platform 22 from the vehicle. Pressure switch 216thereafter prevents movement of platform 22 from the horizontal entrylevel position to the vertically stowed position if the fold input isselected. Selection of the down input moves platform 22 from thehorizontal entry level position to the ground level position where thewheelchair passenger exits the lift. Another wheelchair passenger maythen board the lift, and platform 22 raised from the ground levelposition to the entry level position by selecting the up input. Thewheelchair passenger on platform 22 can then enter the vehicle. Again,pressure switch 216 prevents platform 22 from being moved from thehorizontal entry level position to the vertically stowed position untilthe wheelchair is off of platform 22. When platform 22 is clear ofpassengers, the fold input can be selected to move platform 22 to thevertically stowed position. Further examples and discussion regardingpressure switch 216 are provided in U.S. patent application Ser. No.09/430,436 which is incorporated herein by reference in its entirety.

It is also contemplated that the fold and unfold inputs of signal inputdevice can be integrated into a single input, and that the up and downinputs can be integrated into a single input. The single unfold/foldinput would unfold the platform if the platform is determined to be in afolded condition, and fold the platform if the platform is determined tobe at horizontal transfer level position. Activation of the singleup/down input will lower the platform if the platform is determined tobe in a horizontal entry level position, and raise the platform if theplatform is determined to be at the ground level position. Platformmovement can be stopped and reversed by providing a second input afterinitial movement has been initiated.

It is contemplated that the fold and unfold inputs and up and downinputs on signal input device 212 can be momentary contact switches thatrequire the operator to hold the switch closed for platform movement toa desired position. If the operator releases the switch, then platformmovement stops immediately. When the switch is again activated, platformoperation continues toward the desired position so long as the operatormaintains the switch closed.

It is also contemplated that the fold and unfold inputs and the up anddown inputs on the input control device can be continuous contactswitches that require the operator to activate the switch for platformmovement. If the operator releases the switch, platform movementcontinues to the appropriate vertically stowed, horizontal entry levelor ground level position unless the switch is reactivated or a stopsignal is received.

A further embodiment of safety belt system 200 contemplates providing analarm to signal disengagement of safety belt 202 from buckle 204. Thealarm could be an audio signal and/or visual signal to the operator. Thealarm would notify the operator that safety belt 202 is unbuckled sothat the operator can take an appropriate action. For example, uponindication that safety belt 202 is unbuckled, the operator may want toimmediately stop platform movement by providing the appropriate signalthrough signal input device 212. For embodiments in which input deviceincludes momentary contact switches, the operator could simply releasethe switch to stop platform movement intermediate one of the mainpositions. In another example, the operator may desire that platformmovement continue to one of the main positions. For embodiments in whichinput device includes momentary contact switches, the operator couldsimply maintain the switch in the closed position to continue platformmovement to the next main position.

A further embodiment of safety belt system 200 includes a safety beltlocling system that prevents unbuckling of safety belt 202 from buckle204 during platform movement. Such an interlock device would receive asignal from electrical system 210 that platform movement has beeninitiated, and would thereupon lock safety belt 202 to buckle 204. Onceplatform movement has stopped by reaching one of the main positions, orhas been stopped by the operator, safety belt 202 would automaticallyunlock from buckle 204, and could thereafter be unbuckled.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

1. An assembly capable of moving a passenger from a first surface to anadjacent second surface wherein the surfaces are located at differentvertical levels, the assembly comprising an electrical system; aplatform moveable to transport the passenger between the surfaces, theplatform having an inboard end, an outboard end, and two opposing sides,the inboard end closer to the first surface than the outboard end; anarm coupled to the platform and to the first surface, the arm moveablethrough a first path to transfer the platform between the surfaces; apassenger support located above the platform; a safety restraint systemcoupled to the passenger support, the safety restraint systemcomprising: a belt coupled to the passenger support in a first location;a buckle releasably engagable with the belt and coupled to the passengersupport in a second location, the buckle having a current path coupledto the electrical system of the motive source, the current path havingan open state and a closed state defined in part upon the releasableengagement between the buckle and the belt, the current path closed uponengagement between the buckle and the belt; and a motive source coupledto the electrical system and operable to move the arm through the firstpath, the motive source incapable of initiating movement of the arm whenthe current path is open and capable of initiating movement when thecurrent path is closed, the motive source capable of continuing movementof the arm regardless of the current path state once movement isinitiated.
 2. The assembly as recited in claim 1, wherein the platformfurther comprises side barriers located near the opposing sides and aroll stop located near the outboard end.
 3. The assembly as recited inclaim 2, wherein the roll stop is biased between two positions, thefirst position allowing items to be rolled on or off the outboard endand the second position preventing item from rolling on or off theoutboard end.
 4. The assembly as recited in claim 1, further comprisinga bridge plate pivotally coupled to the inboard end of the platform andpositionable to bridge a gap between the platform and the first surface.5. The assembly as recited in claim 1, further comprising an articulatedlever assembly coupled to the platform, the lever assembly capable ofmoving the platform from a substantially horizontal position to asubstantially vertical position.
 6. The assembly as recited in claim 5,further comprising a pressure switch coupled to the platform, thepressure switch prevents the platform from moving to the verticalposition when the passenger is on the platform.
 7. The assembly asrecited in claim 1, wherein the motive source comprises a hydraulic pumpin fluid communication with a hydraulic cylinder coupled to the arm. 8.The assembly as recited in claim 1, wherein the safety restraint systemfurther comprises a current flow control device coupled to the currentpath, the current flow control device comprising an silicon controlledrectifier diode that controls current flow to the motive source.
 9. Theassembly as recited in claim 1, wherein the safety restraint systemfurther comprises a lock coupled to the buckle and the belt, the lockpreventing disengagement between the belt and the buckle during movementof the platform.
 10. The assembly as recited in claim 1, furthercomprising an alarm coupled to the safety restraint system, the alarmoperable to indicate disengagement between the buckle and the belt. 11.A safety restraint system usable with an electrically operated liftsystem, the safety restraint system comprising: a belt; and a bucklereleasably engagable with the belt and having a current path coupled tothe electrically operated lift system, the current path having an openstate and a closed state defined in part upon the releasable engagementbetween the buckle and the belt, the current path closed upon engagementbetween the buckle and the belt, the electrically operated lift systemincapable of initiating movement when the current path is open andcapable of initiating movement when the current path is closed, theelectrically operated lift system capable of continuing movementregardless of the current path state once movement is initiated.
 12. Theassembly as recited in claim 11, wherein the safety restraint systemfurther comprises a current flow control device coupled to the currentpath, the current flow control device comprising a silicon controlledrectifier diode that controls current flow to the electrically operatedlift system.
 13. The assembly as recited in claim 11, wherein the safetyrestraint system further comprises a lock coupled to the buckle and thebelt, the lock preventing disengagement between the belt and the buckleduring movement of the platform.
 14. The assembly as recited in claim11, further comprising an alarm coupled to the safety restraint system,the alarm operable to indicate disengagement between the buckle and thebelt.
 15. A lift mountable onto a vehicle for transporting a passengerbetween the floor of the vehicle and the street, the lift comprising: aplatform coupled to the vehicle and moveable between the floor and thestreet, the platform having an inboard and an outboard end, the inboardend closer to the first surface than the outboard end; a linkage definedin part by two arms pivotally coupled between the platform and thefloor, the arms of the linkage moveable through a range of motion; anelectrically operated drive system coupled to the linkage andactuateable to move the linkage through the range of motion; a pair ofhandrails coupled to the platform; a buckle coupled to one of the pairof handrails; a belt coupled to the other of the pair of handrails andremoveably engaged with the buckle, the buckle and the belt having anengaged state and a disengaged state; and a user manipulable switchcoupled to the electrically operated drive system, the switch having anopen condition and a closed condition, the drive system incapable ofinitiating actuation when the switch is in the closed condition and thebuckle and belt are in the disengaged state, the drive system capable ofinitiating actuation when the switch is in the closed condition and thebuckle and belt are in the engaged state, and the drive system capableof continuing actuation once begun when the switch is in the closedcondition and the buckle and belt are in the disengaged state.
 16. Theassembly as recited in claim 15, wherein the platform further comprisesa roll stop located near the outboard end, the roll stop is biasedbetween two positions, the first position allowing items to be rolled onor off the outboard end and the second position preventing items fromrolling on or off the outboard end.
 17. The assembly as recited in claim15, further comprising a bridge plate pivotally coupled to the inboardend of the platform and positionable to bridge a gap between theplatform and the vehicle floor.
 18. The assembly as recited in claim 15,further comprising an articulated lever assembly coupled to theplatform, the lever assembly capable of moving the platform from asubstantially horizontal position to a substantially vertical position.19. The assembly as recited in claim 18, further comprising a pressureswitch coupled to the platform, the pressure switch prevents theplatform from moving to the vertical position when the passenger is onthe platform.
 20. The assembly as recited in claim 15, wherein the drivesystem comprises a hydraulic pump in fluid communication with ahydraulic cylinder coupled to the linkage.
 21. The assembly as recitedin claim 15, further comprising a current flow control device coupled tothe electrically operated drive system, the current flow control devicecomprising an silicon controlled rectifier diode that controls currentflow to the drive system.
 22. The assembly as recited in claim 15,further comprising a lock coupled to the buckle and the belt, the lockpreventing disengagement between the belt and the buckle during movementof the platform.
 23. The assembly as recited in claim 15, furthercomprising an alarm coupled to the buckle, the alarm operable toindicate disengagement between the buckle and the belt.
 24. A method ofmoving a passenger between the ground and a vehicle, the methodcomprising: moving the passenger onto a platform coupled to the vehicle;buckling a seatbelt about the passenger; actuating a switch to operatean electrical motive source coupled to the platform, the motive sourceinoperable to move the platform from an at rest position without theseatbelt fastened and operable to move the platform from an at restposition with the seatbelt fastened, the motive source capable of beingcontinually operable as the platform is moving regardless of theseatbelt being fastened; powering the motive source; lifting theplatform and the passenger between the ground and the vehicle; andmoving the passenger off the platform.